1. Field of the Invention
The present invention relates to a treatment liquid for inkjet recording, an ink set, and an inkjet recording method.
2. Description of the Related Art
It has been generally known in an inkjet recording system that a treatment liquid is applied on a recording medium in advance, and a colorant in an aqueous recording ink is aggregated by bringing the treatment liquid with the aqueous recording ink, in order to improve image density. As for a component for aggregating a colorant in an aqueous recording ink, for example, a cationic resin is known. The cationic resin has an index, which is called a cationization degree, and indicates the strength of cationy. The ability of aggregating a colorant in an aqueous recording ink is higher, as the cationization degree is higher. On the other hand, the high cationization degree causes a demerit, such as stronger irritation and sensitization to skin. However, an ink causes a defect, called beading, where adjacent dots are blended to each other, particularly when a recording ink of non-ink absorbency or low absorbency is used, unless the ink contains a cationic resin having a high cationization degree. When cationic resins having the same peaks in the molecular weight distributions thereof are used in a treatment liquid, a smooth film is formed on a surface of a recording medium. Therefore, a friction coefficient between the recording media is high when the recording media are brought into contact with each other, which causes problems, such as an image formed on the recording medium is smeared, and the recording medium itself is torn.
For example, the liquid composition disclosed in Japanese Patent Application Laid-Open (JP-A) No. 2012-126056, and a print pretreatment liquid disclosed in JP-A No. 2004-243624 each contain one cationic resin. Therefore, they cause problems, such as smearing of an image on a recording medium, and tearing the recording medium itself, when they are used particularly on the recording medium of a non-ink absorbency, or low absorbency.
Moreover, the liquid composition disclosed in Japanese Patent (JP-B) No. 3618825 contains two types of cationic resins each having different peaks of the molecular weight distribution, but has a problem in safety, as the molecular weight of the one cationic resin is 1,000 or less.
Moreover, JP-A No. 2012-086380 discloses a treatment liquid containing two-types of cationic resins.
None of the aforementioned literatures describes a cationization degree of a cationic resin for use, and an amount of the cationic resin used therein is 20% by mass at most. Therefore, beading occurs, when the treatment liquid is used particularly on a recording medium of non-ink absorbency, or low absorbency.